title: Contribution of sams-1 and pmt-1 to lipid homoeostasis in adult Caenorhabditis elegans.
abstract: Accumulation of lipids inside the cell is primarily caused by disorders of lipid metabolism. S-adenosylmethionine synthetase (SAMS) produces SAM, an important methyl donor in various phospholipid methyltransferase reactions catalysed by phosphoethanolamine N-methyltransferase (PMT-1). A gel-based, quantitative proteomic analysis of the RNA interference (RNAi)-mediated inactivation of the pod-2 gene, which encodes acetyl-CoA carboxylase, showed a substantial down-regulation of SAMS-1. Consequently, RNAi of either sams-1 or pmt-1 caused a significant increase in lipid droplet size in the intestine of Caenorhabditis elegans. Lipid droplets exhibited increased triacylglycerol (TG) and decreased phosphatidylcholine (PC) levels, suggesting a reciprocal relationship between TG and PC regulation. These lipid-associated phenotypes were rescued by choline feeding. Among the five fat metabolism-related genes examined, two genes were highly induced by inactivation of sams-1 or pmt-1: pod-2 and stearoyl-CoA desaturase (fat-7). Thus, both SAMS-1 and PMT-1 were shown to contribute to the homoeostasis of TG and PC levels in C. elegans, which would provide an important survival strategy under harsh environmental conditions.
authors.affiliation: Department of Biochemistry, College of Life Science and Biotechnology, World Class University Program of Graduate School, Yonsei Proteome Research Center, Yonsei University, 134 Shinchon-dong, Sudaemoon-ku, Seoul, 120-749, Korea.
authors.forename: Yingxiu
authors.initials: Y
authors.lastname: Li
authors.forename: Keun
authors.initials: K
authors.lastname: Na
authors.forename: Hyoung-Joo
authors.initials: HJ
authors.lastname: Lee
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Lee
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Paik
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000166:cytology / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006706:Homeostasis; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008716:Methionine Adenosyltransferase / Q000235:genetics / Q000378:metabolism*; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D020543:Proteome / Q000032:analysis; D034622:RNA Interference
chemical_list: D029742:Caenorhabditis elegans Proteins; D008055:Lipids; D020543:Proteome; D008780:Methyltransferases; C102844:phosphoethanolamine methyltransferase; D008716:Methionine Adenosyltransferase; D002794:Choline